Pharmacokinetics and pharmacodynamics of GS-9350: a novel pharmacokinetic enhancer without anti-HIV activity

GS-9350 is a new chemical entity under development as a potent, mechanism-based inhibitor of human cytochrome P450 3A (CYP3A) isoforms. Its intended use is to increase the systemic exposure of coadministered agents that are metabolized by CYP3A enzymes. Unlike ritonavir, which is in current clinical use for this purpose, GS-9350 is devoid of anti-HIV activity. The pharmacokinetics of GS-9350 and its efficacy in increasing systemic exposure of the probe CYP3A substrate midazolam were examined in a study involving single- and multiple-dose escalations of GS-9350 from 50 to 400 mg. Single-dose escalation from 50 to 400 mg resulted in a 164-fold increase in GS-9350 exposure, whereas multiple-dose escalation in the dosage range of 50-300 mg resulted in a 47-fold increase in exposure. GS-9350 potently inhibited midazolam apparent clearance (95% reduction), similar in effect to ritonavir 100 mg. GS-9350 was generally well tolerated at all doses, and there was no evidence of dose-limiting toxicity. Establishing proof-of-concept, GS-9350 is currently under phase II development as a potential alternative to ritonavir for use with antiretroviral agents (including the HIV integrase inhibitor elvitegravir) that are often prescribed along with a "booster" drug.

Changes in the prevalence of asthma in adults since 1966: the Busselton health study

Asthma prevalence has increased worldwide; although less so in developed countries recently. This study assessed changes in the prevalence of asthma and related symptoms in the Busselton community since 1966. Cross-sectional respiratory health surveys of Busselton adults were conducted in 1966, 1969, 1972, 1975, 1981, 1990 and 2005-2007. Logistic regression models were used to estimate prevalence rates of asthma, respiratory symptoms, smoking, airway hyperresponsiveness (AHR) and atopy and to make comparisons in 2005-2007 and previous survey years. Asthma was defined as ever having doctor-diagnosed asthma (DDA). The prevalence of DDA was around 6% from 1966 to 1975, 8% in 1981 and rose to 19% in 2005-2007. From 1981 to 2005-2007, smoking prevalence declined and obesity and atopy increased but changes in these variables explained only a small part of the increase in DDA. Wheeze and cough/phlegm increased but AHR, breathlessness and doctor-diagnosed bronchitis remained relatively stable over the same period. These observations indicate that the increase in DDA is partly explained by increased symptoms and atopy. The lack of changes in AHR and doctor-diagnosed bronchitis suggests that factors such as diagnostic transfer and increased awareness of asthma have also contributed to the rise in prevalence of DDA.

The PHF11 gene is not associated with asthma or asthma phenotypes in two independent populations

BACKGROUND

Numerous areas of the human genome have previously been associated with asthma and asthma-related phenotypes, but few positive findings have been successfully replicated in independent populations. Initial studies have reported strong associations of variants in the plant homeodomain zinc finger protein 11 (PHF11) gene with serum IgE levels, asthma, airway hyper-responsiveness and childhood atopic dermatitis.

OBJECTIVES

To investigate the association of variants in the PHF11 gene with asthma and associated intermediate phenotypes in two independent Western Australian population-based samples.

METHODS

A linkage-disequilibrium (LD)-tagging set of 20 single nucleotide polymorphisms (SNPs) was genotyped in PHF11 in two separate populations (total n = 2315), a family-based twin study consisting of 230 families (n = 992 subjects) and a population-based nested case-control study consisting of 617 asthma cases and 706 controls. Information regarding asthma, respiratory physiology, atopy and environmental exposures was collected. Transmission disequilibrium tests, variance components models and generalised linear models were used to test for association between PHF11 SNPs and selected asthma outcomes (including longitudinal change in lung function).

RESULTS

After correction for multiple testing, no statistically significant (p < 0.05) associations were found between PHF11 and either asthma or total serum IgE levels in either population. No statistically significant associations were found with any other asthma-associated phenotypes in either population.

CONCLUSIONS

Previously reported associations of PHF11 with asthma outcomes were not replicated in this study. This study suggests that PHF11 is unlikely to contain polymorphic loci that have a major impact on asthma susceptibility in our populations.

Dose-response of ritonavir on hepatic CYP3A activity and elvitegravir oral exposure

Ritonavir, a potent inhibitor of cytochrome P450 isoform 3A (CYP3A) activity, is frequently used to boost the effects of protease inhibitors at doses of 100-400 mg per day; however, human data regarding the optimal dose required for boosting are limited. This study systematically evaluated the ritonavir dose-response relationship on presystemic and systemic CYP3A metabolism using the human immunodeficiency virus integrase inhibitor elvitegravir and midazolam as probe substrates. Ritonavir administered once daily with elvitegravir exhibited nonlinear pharmacokinetics, with a 119-fold increase in the area under the plasma concentration-time curve over the dosing interval over a 20- to 200-mg dose range. The 20-mg dose of ritonavir substantially reduced CYP3A-mediated clearance (CL), as evidenced by a 66% reduction in midazolam CL that plateaued to 17% of baseline activity at a 100-mg dose. Maximum inhibition of elvitegravir apparent oral CL was achieved with ritonavir doses of 50-100 mg. Elvitegravir and ritonavir were generally well tolerated in this study. These data provide a critical understanding of ritonavir's dose-response relationship for inhibition of CYP3A activity in humans.

A genome-wide association scan for asthma in a general Australian population

To date, almost every chromosome has been implicated in genetic susceptibility to asthma to some degree. When compared with single nucleotide polymorphism, microsatellite markers exhibit high levels of heterozygosity and therefore provide higher statistical power in association. The objective of this study was to perform a genome-wide association study using 23,465 in-house microsatellite markers to detect asthma susceptibility regions in the Busselton population. In this study, three separate pooled DNA screenings yielded 18 markers with significantly different estimated frequencies in the three separate "case and control" pools: each pool consisting of 60 males and 60 females. These markers were evaluated by individual typing in 360 cases and 360 controls. Two markers showed significant differences between cases and controls (P = 0.001 and P = 0.003). Regions surrounding the two markers were subjected to high-density association mapping with a total of 14 additional markers. We were able to confirm and fine map the association in these two regions by typing 14 additional microsatellite markers (1805A09 (D18S0325i), P = 0.002; 1806D05 (D18S0181i), P = 0.001). Each region contains a predicted gene that showed strong associations with asthma. Further studies are underway to characterize the novel candidate asthma susceptibility genes identified in this genome-wide study.

AluyMICB dimorphism within the class I region of the major histocompatibility complex is associated with asthma and airflow obstruction in the Busselton population

AIM

To examine the association between the Alu dimorphism within the first intron of the MICB gene and asthma and airflow obstruction. Background The highly polymorphic non-classical MHC class I polypeptide-related (MIC) genes, MICA and MICB, encode stress inducible glycoproteins, which are expressed on a variety of epithelial cells, including those of the lungs.

METHODS

AluyMICB genotyping was performed on 1109 subjects from the Busselton Health Study. From a standard questionnaire, 359 individuals indicated that they had been diagnosed by a doctor with asthma. Lung function was assessed by the forced expired volume in 1 second (FEV1) and expressed as a percent of the predicted value. Airflow obstruction was defined as FEV1<80% predicted.

RESULTS

In men, a dominant relationship was found between the AluyMICB DD genotype and asthma (P=0.006; chi2(2)=7.65). Furthermore, multivariate analysis adjusted for age, height, weight and body mass index (BMI) showed a relationship between DD genotype and asthma in men in a dominant model (odds ratio (OR)=1.97; 95% confidence interval (CI)=1.11-3.51; P=0.021). In women, an association was found between the AluyMICB II genotype and FEV1 percent predicted as a continuous variable (P=0.001). When adjusted for age and BMI, it showed a significant relationship between AluyMICB and airflow obstruction in a dominant model (OR=14.11%, 95% CI 3.29-60.57, P<0.001). However, no association was found between the AluyMICB II genotypes and airflow obstruction in men.

CONCLUSION

These findings suggest the possible involvement of a MHC class I gene in abnormal airway structure in women and airway function in men.

Fever, pulmonary haemorrhage, and acute renal failure in a young girl

Leptospirosis is rarely reported in children. It is easily treated with antibiotics but can be fatal if treatment is delayed. A 12-year-old girl was diagnosed with Weil syndrome, a severe form of leptospirosis, 10 days after returning from Mainland China. She presented with fever, hypotension, jaundice, and acute renal failure. She had used well water for bathing and swum in freshwater.

Infection control for SARS in a tertiary paediatric centre in Hong Kong

Severe acute respiratory syndrome (SARS) is an emerging infectious disease. After the appearance of an index patient in Hong Kong in February 2003, SARS outbreaks occurred rapidly in hospitals and spread to the community. The aim of this retrospective study is to evaluate the effectiveness of a triage policy and risk-stratified infection control measures in preventing nosocomial SARS infection among paediatric healthcare workers (HCWs) at the Prince of Wales Hospital, a general hospital to which children with SARS are referred in Hong Kong. The acute paediatric wards were stratified into three areas: (1) ultra high-risk area, (2) high-risk area and (3) moderate-risk area according to different risk levels of nosocomial SARS transmission. The implementation of different levels of infection control precautions was guided by this risk stratification strategy. Between 13 March and 23 June, 38 patients with probable and suspected SARS, 90 patients with non-SARS pneumonia, and 510 patients without pneumonia were admitted into our unit. All probable SARS cases were isolated in negative-pressure rooms. Twenty-six HCWs worked in the ultra high-risk area caring for SARS patients and 88 HCWs managed non-SARS patients in other ward areas. None of the HCWs developed clinical features suggestive of SARS. In addition, there was no nosocomial spread of SARS-associated coronavirus to other patients or visitors during this period. In conclusion, stringent infection control precautions, appropriate triage and prompt isolation of potential SARS patients may have contributed to a lack of nosocomial spread and HCW acquisition of SARS in our unit.

Identification of two new C4 alleles by DNA sequencing and evidence for a historical recombination of serologically defined C4A and C4B alleles

Nucleotide polymorphisms of the C4 genes were investigated by direct sequencing of seven different homozygous typing cells from the 10IHW panels. Two novel sequences were identified within the C4d region of the C4 genes. Our sequencing analyses extend previous findings suggesting that a recombination hot spot is likely to have occurred between codon positions 1157 and 1186 within the C4d region. The classification of electrophoretically defined C4A and C4B alleles can be further subtyped by sequencing. Because the central major histocompatibility complex region that carries various copies of the C4 gene has been associated with a range of disorders; further analysis at the sequence level within the C4 locus may provide informative genetic markers for the investigation of disease-associated polymorphisms.

Red eyes as the initial presentation of systemic meningococcal infection

The present paper is a report of a 14-month-old boy who presented with fever, coryzal symptoms and red eyes. The patient developed a generalized tonic clonic convulsion on day 2 of his illness. Ophthalmological assessment demonstrated bilateral hypopyon and vitreous opacity resulting from endophthalmitis. Cerebrospinal fluid was positive for Neisseria meningitidis (A, C, Y, W 135) by latex agglutination. He was treated with high dose intravenous cefotaxime and intravitreal ceftazidime. He made good recovery and his vision was preserved. In view of the potential morbidity and mortality associated with systemic meningococcal infection, the presence of red eye and hypopyon provides important diagnostic clues indicating the need to investigate beyond superficial conjunctivitis. It should prompt the clinician to recognize endopthalmitis early and accurately diagnose this serious disease.

Localization of a non-melanoma skin cancer susceptibility region within the major histocompatibility complex by association analysis using microsatellite markers

The major histocompatibility complex (MHC) is known to have a role in the development of non-melanoma skin cancer (NMSC), although the genes and mechanisms involved have yet to be determined. To identify the susceptibility locus for NMSC within the MHC, we used a collection of well-defined polymorphic microsatellite markers from the Human leucocyte antigen (HLA) region for an association analysis of 150 cases with NMSC and 200 healthy controls selected from the Busselton population in Western Australia. High-resolution mapping was undertaken using a total of 40 highly polymorphic markers located at regular intervals across the HLA region (3.6Mb). Polymerase chain reaction (PCR) analysis was initially performed on pooled DNA markers to detect those markers that showed different allele profiles. Statistically significant differences in allelic frequencies (differentiating alleles) were found between cases and controls at three polymorphic microsatellite loci within a 470-kb genomic susceptibility region ranging between 6 kb centromeric of the HLA-B gene and intron 5 of the DDR gene. Interestingly, this genome region corresponded completely with the psoriasis-susceptibility locus. The three differentiating alleles and another four markers outside the susceptibility region were then PCR tested by individual genotyping of cases and controls. The newly identified susceptibility locus for NMSC within the MHC was found to be significantly different between the cases and controls by comparisons of allele frequencies at the three differentiating loci estimated from DNA pools and then confirmed by individual genotyping. This is the first study using high density microsatellite markers to localize a NMSC susceptibility region within the human genome.

3-methyglutaconic aciduria in a Chinese patient with glycogen storage disease Ib

We report elevated urinary excretion of 3-methylglutaconic (3MGC) and 3-methylglutaric acids (3MGR) in a patient with glycogen storage disease Ib. Combined excretion was 10-fold elevated in comparison to control during inadequate glucose maintenance, and still elevated following dietary improvement. 3MGC acid excretion correlated with plasma lactate and glucose. We speculate that imbalanced gluconeogenesis and de novo cholesterol synthesis result in secondarily increased 3MGC/3MGR production.

Corneodesmosin DNA polymorphisms in MHC haplotypes and Japanese patients with psoriasis

In order to examine the relationship between corneodesmosin (CDSN) and psoriasis we have determined the presence of CDSN polymorphisms by DNA sequencing in (a) nine B-LCL cell lines of major histocompatibility complex ancestral haplotypes known to be associated with psoriasis vulgaris including 13.1AH, 46.1AH, 46.2 and 57.1AH, and in (b) a group of 267 unrelated individuals comprising Japanese psoriasis patients (n = 101) and Japanese subjects without the disease (n = 166). Three novel CDSN gene sequences were identified. In addition, we have classified the 18 alleles into seven main groups based on phylogeny of non-synonymous substitutions. However, we have found no statistically significant differences between the patients and the unaffected individuals in any of these groups. These findings indicate that CDSN is not a major psoriasis susceptibility gene.

Overview of common inherited metabolic diseases in a Southern Chinese population of Hong Kong

BACKGROUND

The Joint metabolic clinic at the Prince of Wales Hospital was established in January 1997 to provide a comprehensive multi-disciplinary care to patients with inherited metabolic diseases (IMDs). Patients are referred from both within and outside our hospital. Until July, 2000, more than 40 patients and families with 20 different biochemical diagnoses attend the clinic for regular follow up. A pattern of more common IMDs among Hong Kong Chinese emerged from our case registry. In order to advance the understanding of Chinese metabolic diseases, we examined the molecular basis of those diseases with unique features in Chinese or were locally prevalent. Mutations were found in patients with primary carnitine deficiency, ornithine transcarbamylase deficiency, X-linked adrenoleukodystrophy, glutaric aciduria type I, and galactosemia. We also analyzed the mutations in multiple carboxylase deficiency and Niemann-pick type C on four families.

CONCLUSIONS

Although IMDs are a significant cause of mortality and morbidity among pediatric patients, with a better understanding of the molecular genetics of these diseases, prenatal diagnosis of these common IMDs will be facilitated, which is currently the most effective way of controlling IMDs.

Pharmaceutical significance of the cyclic imide form of recombinant human glial cell line derived neurotrophic factor

PURPOSE

The purpose of this paper is to determine the significance of cyclic imide formation of an aspartic acid residue during storage on the pharmaceutical quality of a recombinant human glial cell line-derived neurotrophic factor (rhGDNF) formulation.

METHODS

A combination of chromatography, peptide mapping, mass spectroscopy, and protein sequencing was used to purify and characterize the degradation product. Circular dichroism, 1,8-ANS and heparin binding, melting temperature determination, bioassays, and preclinical pharmacokinetic and toxicology testing were performed to examine its equivalence to native rhGDNF.

RESULTS

The rhGDNF with cyclic imide at aspartic acid residue 96 showed identical activity, structure, pharmacokinetic profile, and toxicity profile to the native rhGDNF.

CONCLUSIONS

Formation of cyclic imide at aspartic acid residue 96 does not affect the pharmaceutical quality of the rhGDNF formulation.

Ocular complications of paediatric patients with nephrotic syndrome

PURPOSE

To investigate ocular complications arising from nephrotic syndrome and/or its treatments in children.

METHODS

A cross-sectional study was conducted in a teaching hospital. A total of 31 paediatric patients with nephrotic syndrome were studied. Comprehensive ophthalmic assessments on best-corrected visual acuity, intraocular pressure, slit-lamp and fundus examination were taken. Information regarding histological diagnosis of nephrotic syndrome and its treatment regimen in each patient was reviewed and analysed.

RESULTS

Bilateral posterior subcapsular cataracts were detected in three of 29 patients (10.3%) who received steroid therapy. Two had normal vision while one had visual acuity reduced to 6/15 in both eyes. The age of onset of the nephrotic syndrome in these three patients was 2 years, which was significantly younger than those without cataract (5.4 +/- 3.2 years, P < 0.001). Three patients (9.7%) had isolated asymptomatic fundal findings of tortuous and dilated retinal vessels. Hypertensive retinopathy was found in one patient (3.2%). No steroid-induced glaucoma, uveitis, ocular infection, or other eye complications related to the use of steroids or other immunosuppressive agents were noted.

CONCLUSIONS

Children who have nephrotic syndrome often require prolonged, intermittent high dose of systemic corticosteroid therapy. Paediatricians should be aware of the potential risk of developing steroid-related complications, especially posterior subcapsular cataract. It appears to have a higher risk when steroid therapy is used in very young patients. Early detection would help to prevent amblyopia development, particularly in the group of immature eyes.

Grading of acute and chronic renal lesions in Henoch-Schönlein purpura

The renal outcome of 34 patients with Henoch-Schönlein purpura nephritis was assessed clinically and by grading acute and chronic renal lesions using a system we applied to primary IgA nephropathy. On a median follow-up period of 65 months, hypertension and the serum levels of creatinine and proteinuria at the time of renal biopsy were correlated with renal survival. Acute glomerular lesions including mesangial hypercellularity, endocapillary proliferation, necrosis, cellular crescents, and leukocytes infiltration were observed, respectively, in 41%, 12%, 50%, 29%, and 32% of the cases. Of these, only glomerular necrotizing lesion and cellular crescent were correlated with the renal survival. Chronic renal lesions based on a grading system applied to primary IgA nephropathy and assessing the extent of glomerular sclerosis (glomerular grading), of tubular loss and interstitial fibrosis (tubulointerstitial grading), and of hyaline arteriolosclerosis demonstrated correlation between these lesions, as well as with renal survival. On follow-up, these chronic renal lesions were predictors of subsequent clinical events associated with disease progression, such as impaired renal function, significant proteinuria, and development of hypertension. Despite some limitations related to the relatively small size, this series indicates that distinction of acute and chronic lesions of Henoch-Schonlein purpura nephritis is important for both the prognosis and management of patients.

Angiotensin II type 1 receptor modulation of L-type calcium currents in guinea-pig ventricular cells

OBJECTIVE

To study the cellular mechanism of the effect of Ang II on ICa,L in single guinea-pig ventricular cells by using losartan and 1-(5-lsoquinolinylsulfonyl)-2-Methyl-Piperazine (H-7) as the Ang II type 1 receptor (AT1) inhibitor and protein kinase C inhibitor, respectively.

METHODS

Patch clamp techniques were used to study the cellular mechanism of the effect of Ang II on ICa,L in single guinea-pig ventricular cells.

RESULTS

In the whole cell patch clamp recording model, Ang II stimulated ICa,L in a concentration dependent manner; the maximal effect was obtained at 100 nmol/L (n = 9). At 30 nmol/L, Ang II stimulated peak ICa,L from 11.3 +/- 0.6 pA/pF to 15.3 +/- 0.6 pA/pF (at + 10 mV, n = 9, P < 0.05). 100 nmol/L Losartan, a specific AT1 receptor inhibitor, had no effect on ICa,L (n = 9), but the effect of Ang II on ICa,L was inhibited by 100 nmol/L Losartan. Ang II on ICa,L was also inhibited by 20 mumol/L H-7, a specific protein kinase C inhibitor, whereas H-7 alone has no effect on ICa,L (n = 9).

CONCLUSION

Ang II stimulates ICa,L in guinea-pig ventricular cells by binding to AT1 through a transduction pathway involving protein kinase C.

Spontaneous intramural hematoma of stomach

BACKGROUND

Intramural hematoma occurs uncommonly in the gastrointestinal tract and very rarely in the stomach. In case of a spontaneous gastric hematoma, the few previously reported patients all had certain predisposing factors. However, truly spontaneous intramural hematoma of the stomach without an identifiable cause has not been reported before.

METHOD

Emergency total gastrectomy was performed in a 49-year-old man with such pathology and the diagnosis was made postoperatively.

RESULTS

The patient required further laparotomy on day 10 for drainage and debridement of a subphrenic abscess. He recovered uneventfully from the second operation. After an extensive pathological search, no predisposing factors could be found. The patient remains in good health 18 months after the operations.

CONCLUSION

Spontaneous intramural gastric hematoma is extremely rare. But even rarer is when predisposing conditions or lesions are absent.